LP-362 make file logging thread safe (and asynchronous)

ground/gcs/src/app/main.cpp

@@ -84,6 +84,7 @@
 #include "qtsingleapplication.h"
 #include "utils/xmlconfig.h"
 #include "utils/pathutils.h"
+#include "utils/filelogger.h"
 #include "gcssplashscreen.h"
 
 #include <extensionsystem/pluginmanager.h>
@@ -108,7 +109,6 @@
 #include <QSplashScreen>
 #include <QSurfaceFormat>
 
-namespace {
 typedef QList<ExtensionSystem::PluginSpec *> PluginSpecSet;
 typedef QMap<QString, bool> AppOptions;
 typedef QMap<QString, QString> AppOptionValues;
@@ -286,48 +286,21 @@ void systemInit()
     QSurfaceFormat::setDefaultFormat(format);
 }
 
-static QTextStream *logStream;
+static FileLogger *logger;
 
 void mainMessageOutput(QtMsgType type, const QMessageLogContext &context, const QString &msg)
 {
-    Q_UNUSED(context);
-
-    QTextStream &out = *logStream;
-
-    // logStream << QTime::currentTime().toString("hh:mm:ss.zzz ");
-
-    switch (type) {
-    case QtDebugMsg:
-        out << "DBG: ";
-        break;
-#if (QT_VERSION >= QT_VERSION_CHECK(5, 5, 0))
-    case QtInfoMsg:
-        out << "INF: ";
-        break;
-#endif
-    case QtWarningMsg:
-        out << "WRN: ";
-        break;
-    case QtCriticalMsg:
-        out << "CRT: ";
-        break;
-    case QtFatalMsg:
-        out << "FTL: ";
-        break;
-    }
-
-    out << msg << '\n';
-    out.flush();
+    logger->log(type, context, msg);
 }
 
+Q_DECLARE_METATYPE(QtMsgType)
+
 void logInit(QString fileName)
 {
-    QFile *file = new QFile(fileName);
-
-    if (file->open(QIODevice::WriteOnly | QIODevice::Text)) {
-        logStream = new QTextStream(file);
-        qInstallMessageHandler(mainMessageOutput);
-    } else {
+    qRegisterMetaType<QtMsgType>();
+    qInstallMessageHandler(mainMessageOutput);
+    logger = new FileLogger();
+    if (!logger->start(fileName)) {
         displayError(msgLogfileOpenFailed(fileName));
     }
 }
@@ -456,7 +429,6 @@ void loadTranslators(QString language, QTranslator &translator, QTranslator &qtT
         translator.load(QString());
     }
 }
-} // namespace anonymous
 
 int main(int argc, char * *argv)
 {
@@ -494,6 +466,8 @@ int main(int argc, char * *argv)
     if (appOptionValues.contains(LOG_FILE_OPTION)) {
         QString logFileName = appOptionValues.value(LOG_FILE_OPTION);
         logInit(logFileName);
+        // relog command line arguments for the benefit of the file logger...
+        qDebug() << "Command line" << app.arguments();
     }
 
     // load user settings
@@ -644,5 +618,9 @@ int main(int argc, char * *argv)
 
     qDebug() << "main - GCS ran for" << timer.elapsed() << "ms";
 
+    if (logger) {
+        delete logger;
+    }
+
     return ret;
 }

ground/gcs/src/libs/utils/filelogger.h

@@ -0,0 +1,141 @@
+/**
+ ******************************************************************************
+ *
+ * @file       filelogger.h
+ * @author     The LibrePilot Project, http://www.openpilot.org Copyright (C) 2016.
+ *             Parts by Nokia Corporation (qt-info@nokia.com) Copyright (C) 2009.
+ * @brief
+ * @see        The GNU Public License (GPL) Version 3
+ * @defgroup
+ * @{
+ *
+ *****************************************************************************/
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#pragma once
+
+#include "utils_global.h"
+
+#include <QObject>
+#include <QFile>
+#include <QTextStream>
+#include <QThread>
+#include <QDebug>
+
+class QTCREATOR_UTILS_EXPORT FileLogger : public QObject {
+    Q_OBJECT
+
+private:
+    QTextStream * logStream;
+    QThread *loggerThread;
+    bool started;
+
+public:
+    FileLogger() : QObject(), logStream(NULL), loggerThread(NULL), started(false)
+    {}
+
+    virtual ~FileLogger()
+    {
+        stop();
+        if (logStream) {
+            delete logStream;
+        }
+    }
+
+public:
+    bool start(const QString &fileName)
+    {
+        if (started) {
+            return false;
+        }
+
+        QFile *file = new QFile(fileName);
+        if (!file->open(QIODevice::WriteOnly | QIODevice::Text)) {
+            return false;
+        }
+
+        logStream    = new QTextStream(file);
+
+        loggerThread = new QThread(this);
+        moveToThread(loggerThread);
+        loggerThread->start();
+
+        started = true;
+
+        return true;
+    }
+
+    bool stop()
+    {
+        if (!started) {
+            return false;
+        }
+        // stop accepting messages
+        started = false;
+
+        // make sure all messages are flushed by sending a blocking message
+        QtMsgType type    = QtDebugMsg;
+        const QString msg = "stopping file logger";
+        QMetaObject::invokeMethod(this, "doLog", Qt::BlockingQueuedConnection,
+                                  Q_ARG(QtMsgType, type), Q_ARG(const QString &, msg));
+
+        return true;
+    }
+
+    void log(QtMsgType type, const QMessageLogContext &context, const QString &msg)
+    {
+        Q_UNUSED(context);
+
+        if (!started) {
+            return;
+        }
+
+        QMetaObject::invokeMethod(this, "doLog", Qt::QueuedConnection,
+                                  Q_ARG(QtMsgType, type), Q_ARG(const QString &, msg));
+    }
+
+private slots:
+    void doLog(QtMsgType type, const QString &msg)
+    {
+        QTextStream &out = *logStream;
+
+        // logStream << QTime::currentTime().toString("hh:mm:ss.zzz ");
+
+        switch (type) {
+        case QtDebugMsg:
+            out << "DBG: ";
+            break;
+#if (QT_VERSION >= QT_VERSION_CHECK(5, 5, 0))
+        case QtInfoMsg:
+            out << "INF: ";
+            break;
+#endif
+        case QtWarningMsg:
+            out << "WRN: ";
+            break;
+        case QtCriticalMsg:
+            out << "CRT: ";
+            break;
+        case QtFatalMsg:
+            out << "FTL: ";
+            break;
+        }
+
+        out << msg << '\n';
+        out.flush();
+    }
+};

ground/gcs/src/libs/utils/utils.pro

@@ -121,7 +121,8 @@ HEADERS += \
     logfile.h \
     crc.h \
     mustache.h \
-    textbubbleslider.h
+    textbubbleslider.h \
+    filelogger.h
 
 HEADERS += xmlconfig.h